A lot of you I am sure have seen the movie "The Abyss". If not then
it doesn't matter but what is important however, is one of the diving techniques
that they use. This technique is called Liquid Breathing. Until not long
ago, people thought that this was fictitious and was not possible but in fact it
has been around for a lot longer than you might think!

The general type of liquid used by the US Navy and other Navies in the world
generally have a perfluorocarbon type composition. The type of halide attached
onto the molecule depends but it is either fluorine or bromine. However, the
only problem associated with using bromine is that it is a very strong
greenhouse gas but it could be regenerated through special filters and
rebreathers.

ADVANTAGES

It seems like an odd concept but:

1- Due to its density, Liquivent
(marketed name for liquid breathing liquid) can carry as much as 25 times as
much oxygen than blood and it has enormous potential for patients with lung and
breathing disorders.

2- If fluid is taken into the lungs whilst diving, then the pressure in the
body could match that of the pressure of the surrounding water. Thus breathing
would be easier and lower concentrations would only be needed.

3- Thus, this would also eliminate the need for decompression and its
inherent problems i.e. nitrogen narcosis and the bends.

4- A given volume of oxygen-saturated fluorocarbon contains 3 times as much
oxygen as the same volume of air or whole blood.

5- According to the movie "The Abyss", the deepest suit dive was to
4800ft which is equivalent to about 300atmospheres of pressure! Tests with mice
have been done at pressures of up to 8000ft.

HISTORY

This concept originated in the mid 60's when Dr Kylstra a physiologist
realised that salt solutions could be saturated with oxygen at high pressures.
However, after several experiments he concluded that this mixture becomes toxic
due to the build up of carbon dioxide. Therefore, a new mixture that could be
saturated with oxygen and get rid of carbon dioxide quickly and efficiently had
to be thought of.

After further experimentation in 1969, Dr Clark realised that oxygen and
carbon dioxide were very soluble in fluorocarbon liquids like freon. Assuming
the lungs could cope with this material, Dr Clark figured that these
fluorocarbons could support respiration of animals.